Much of the non-arable grasslands in the southern Great Plains (USA) are infested by woody plants that degrade ecosystem stability by reducing herbaceous production and diversity and increasing soil erosion.  In addition, woody infestation causes economic hardships for livestock producers dependent on native rangeland grasses for forage.  Treating invasive woody plants are increasingly uneconomical because of increasing fossil-fuel costs.  A potential solution is to utilize these woody invaders for bioenergy end products such as bioheat and biofuel.  Honey mesquite (Prosopis glandulosa) is a primary candidate because of abundant populations in the region, high potential yield (10-30 Mg/ha), reliable growth during drought, no cultivation costs, and high regrowth capacity following aboveground harvest.  Reducing mesquite competition with grasses after harvest will have the added effect of increasing herbaceous forage production for livestock and restoring rangeland health.  Moreover, harvesting in patterns that mix woodland thickets with harvested patches can improve wildlife habitat.  Harvest studies of different-aged mesquite regrowth found that stems > 3 cm diameter account for 18 % of total tree mass by 7 years and 41 % by 12 years.  Total mass of 12-year regrowth trees was 55 kg, while mass of undisturbed trees of the same height was 33 kg.  Thus, regrowth can produce potentially more standing mass per area.  A mesquite harvester was recently constructed to rapidly harvest dense stands.  Operational efficiency, woody harvest yield relative to pre-harvest standing crop and impacts on soils and herbaceous vegetation of the harvester will be reported.